This program investigates the function of the pulmonary system by combining analytical and experimental in-vitro and in-vivo studies. Investigations relate the cardiac ejection phenomenon, the physics of flow in distorting vessels and specifically the hemodynamics in pulmonary vessels. Projects include: the development of a full non-linear three dimensional analytic flow model for ejection into vessels of altering cross section, varying axial curvature and taper which serves as a model for the pulmonary trunk; physical model studies and experimental validation of the theoretical solution; the effect of axial taper on flow and vascular compliance; a characterization of the branching pulmonary system and a classic theoretical validation of the analytic solution; an evaluation of fluid pressures, wall loading and wall shears in distorting vessels of circular or non-circular cross section; the role of smooth muscle on the function of the pulmonary trunk and an analysis of the pulmonary arterial system as an afterload to the right ventricle. Analysis is followed by experiments involving the behavior of physical models which, in turn, are followed by investigation of real isolated structures and finally interactive effects and control of the integrated system.